We examined the temporal and spatial variation in the abundance and diet composition of Acanthogobius ommaturus at three subhabitats (mudflat, salt marsh, and creek) of the Dongtan wetland of Yangtze Estuary with monthly field samplings from July 2015 to June 2016. The results showed that the samples of A. ommaturus were mainly composed of young individuals in the period of June-November, whereas no fish was collected during the other months. Most of the samples were collected in July (71) and only three individuals was collected in November. Most of the samples were collected (93) in creek, which was 5.2 and 4.9 times of those in mudflat and salt marsh, respectively. The diet of the A. ommaturus included 10 taxa and 30 prey species, dominated by shrimps. In the taxonomic level, the dominant preys were the Exopalaemon annandalei or other Exopalaemon sp. of shrimps, the Sesarma sp. of crabs and Micromecta quadriseta of insects. Compared with other taxonomic groups, the fish prey had relatively higher mass percentage but lower abundance percentage. The prey composition of A. ommaturus differed among subhabitats. The feeding level of A. ommaturus increased gradually from July to November and reached 3.0 in late autumn. The differences in the abundances of A. ommaturus among subhabitats would be induced by prey composition.
2015年7月至2016年6月每月在长江口东滩湿地西南水域的光滩、盐沼(以海三棱藨草为主)和潮沟3种亚生境进行斑尾刺虾虎鱼的样本采集,分析斑尾刺虾虎鱼的丰度和食性差异.结果表明: 6—11月均采集到斑尾刺虾虎鱼样本,以幼鱼为主,其他月份未采集到.其中,7月采集数量最多,为71尾,11月仅采集到3尾.潮沟中共采集到93尾,分别是光滩和盐沼的5.2和4.9倍. 6—11月斑尾刺虾虎鱼的平均体长和体质量均呈逐渐增加趋势.斑尾刺虾虎鱼主要摄食虾类、蟹类、昆虫类和多毛类等10大类30小类饵料生物.其中,虾类是最重要的饵料类别,并以安氏白虾等白虾属为主;蟹类以相手蟹属为主;昆虫类以小划蝽等蝽科昆虫成虫为主;鱼类饵料的质量百分比相对较高,但数量比例很低.不同亚生境斑尾刺虾虎鱼的饵料组成差异较大.7—11月斑尾刺虾虎鱼的摄食等级随体长增大而明显增大,秋末(11月)平均摄食等级可达3.不同亚生境间的斑尾刺虾虎鱼丰度差异与其摄食饵料不同有关.
Keywords: Acanthogobius ommaturus; Yangtze River estuary; diet composition; monthly change.